University of Waterloo

Displaying 1-40 of 139 results

The electrical grid is a critical infrastructure that is slowly moving towards a more reliable and efficient supply system: the Smart Grid. As part of this migration process, a new group of energy-aware and emission-free technologies are being developed. Electric vehicles are a promising technology that belongs to that group....

For the future smart grid, decentralized inverter control is essential in Distributed Generation (DG) micro-grids where a powerful central controller is unavailable for cost and reliability concerns. However, decentralized inverter control suffers from limited system stability mainly because of the lack of communications among different inverters. In this paper, the...

In this paper, the authors introduce a novel Remote Health Monitoring (RHM) system to enable high-quality pervasive healthcare services to users with low delivery delay and reduced costs. They define the RHM architecture and summarize the design considerations. They then present a promising commercialized solution, ViiCare, with system infrastructures and...

The authors implement asymmetric pairings derived from Kachisa-Schaefer-Scott (KSS), Barreto-Naehrig (BN), and Barreto-Lynn-Scott (BLS) elliptic curves at the 192-bit security level. Somewhat surprisingly, they find pairings derived from BLS curves with embedding degree 12 to be the fastest for their serial as well as their parallel implementations. The serial implementations...

The authors consider the problem of managing a bounded size First-In-First-Out (FIFO) queue buffer, where each incoming unit-sized packet requires several rounds of processing before it can be transmitted out. Their objective is to maximize the total number of successfully transmitted packets. They consider both push-out (when the policy is...

Cognitive radio is a promising approach for efficient utilization of radio spectrum. Due to its high spectral efficiency and flexibility, OFDM is considered as a good signaling scheme for cognitive radios. In this paper, the authors investigate the problem of cross-band interference minimization in OFDM-based cognitive systems. Cross-band interference is...

The future smart grid is expected to be an integration of intelligent microgrids featured by localized electricity generation, storage, and consumption. Wireless communication is a promising means to facilitate pervasive microgrid monitoring and control at a high flexibility and low deployment cost. In order to avoid a single point of...

Delay/Disruption Tolerant Networks (DTNs) are self-organized wireless ad-hoc networks, where end-to-end connectivity can not be guaranteed and communications rely on the assumption that the nodes are willing to store-carry-and-forward bundles in an opportunistic way. However, this assumption would be easily violated due to the selfish nodes which are unwilling to...

The authors give a protocol for multi-server information-theoretic private information retrieval which achieves the theoretical limit for Byzantine robustness. That is, the protocol can allow a client to successfully complete queries and identify server misbehavior in the presence of the maximum possible number of malicious servers. They have implemented their...

This paper investigates a new approach to analyze symmetric ciphers by dividing the algorithms to consecutive sub-ciphers and then evaluating them separately. This attack is suitable for ciphers with simple key schedules and having block sizes smaller than key lengths. The authors have successfully applied this multidimensional approach to the...

Smart community is an emerging Internet of Things application. It supports a variety of high-value automated services such as pervasive healthcare through a multi-hop community network of smart homes in a local residential region. In this paper, the authors study privacy preserving data communication between patients and an online healthcare...

Without direct path, information delivery in sparse Delay Tolerant Networks (DTNs) typically relies on intermittent relays, making the transmission not only unreliable but also time consuming. To make the matter even worse, the source nodes may transmit some encrypted "Junk" information, similar as the spam emails in current mail systems,...

In this paper, the authors propose a distributed Prediction-based Secure and Reliable routing framework (PSR) for emerging Wireless Body Area Networks (WBANs). It can be integrated with a specific routing protocol to improve the latter's reliability and prevent data injection attacks during data communication. In PSR, using past link quality...

Collaborative spectrum sensing has been regarded as a promising approach to enable secondary users to detect primary users by exploiting spatial diversity. In this paper, the authors consider a converse question: could space diversity be exploited by a malicious entity, e.g., an external attacker or an untrusted Fusion Center (FC),...

Barrier coverage problem in emerging mobile sensor networks has been an interesting research issue. Existing solutions to this problem aim to decide one-time movement for individual sensors to construct as many barriers as possible, which may not work well when there are no sufficient sensors to form a single barrier....

A quadrature signaling based two-phase cooperation framework for cooperative cognitive radio networking is proposed. By leveraging the degrees of freedom provided by orthogonal modulation, secondary users are able to relay the traffic of primary users and transmit their own in the same time slot without interference. To evaluate the cooperation...

Specification and maintenance of relationships between models are vital for MDE. The authors show that a wide class of such relationships can be specified in a compact and precise manner, if inter-model mappings are allowed to link derived model elements computed by corresponding queries. Composition of such mappings is not...

In this paper, the inherent drawbacks of the naive lattice decoding for MIMO fading systems is investigated. The authors show that using the naive lattice decoding for MIMO systems has considerable deficiencies in terms of the rate-diversity trade-off. Unlike the case of maximum-likelihood decoding, in this case, even the perfect...

A new viewpoint for adopting the lattice reduction in communication over MIMO broadcast channels is introduced. Lattice basis reduction helps one to reduce the average transmitted energy by modifying the region which includes the constellation points. Also, the outage probability for both cases of fixed-rate users and fixed sum-rate is...

Diversity order is an important measure for the performance of communication systems over MIMO fading channels. In this paper, the authors prove that in MIMO multiple access systems (or MIMO point-to-point systems with V-BLAST transmission), lattice-reduction-aided decoding achieves the maximum receive diversity (which is equal to the number of receive...

Exploiting the residual redundancy in a source coder output stream during the decoding process has been proven to be a bandwidth efficient way to combat the noisy channel degradations. In this paper, the authors consider soft reconstruction of speech spectrum, in GSM Adaptive Multi-Rate and IS-641 vocoders, transmitted over a...

In this paper, a method is proposed to construct spectral-efficient unitary space-time codes for high-rate differential communications over multiple-antenna channels. Unlike most of the known methods which are designed to maximize the diversity product (the minimum determinant distance), the authors' objective is to increase the spectral efficiency. The simulation results...

In the standard definition of a commitment scheme, the sender commits to a message and immediately sends the commitment to the recipient interested in it. However, the sender may not always know at the time of commitment who will become interested in verifying it. Further, when the interested party does...

The authors focus on efficient algorithms for resource allocation problems in large wireless networks. They first investigate the link scheduling problem and identify the properties that make it possible to compute solutions efficiently. They, then show that the node on-off scheduling problem shares these features and is amenable to the...

The authors consider User-Private Information Retrieval (UPIR), an interesting alternative to Private Information Retrieval (PIR) introduced by Domingo-Ferrer et al.. In UPIR, the database knows which records have been retrieved, but does not know the identity of the person making the query. The goal of UPIR, then, is to disguise...

Throughput and lifetime are both crucial design objectives for multi-hop wireless networks. In general, it is not sufficient to optimize either of them separately. As these two objectives are often conflicting with each other, the authors can only hope to identify the tradeoffs between them. This entails a harder problem...

Recent advances in micro electro mechanical systems and wireless communication have paved the way for the rapid deployment of wireless sensor networks, which have been well recognized as a ubiquitous and general approach for some emerging applications such as real-time traffic monitoring, ecosystem and battlefield surveillance. Typically, a wireless sensor...

Cloud computing confers strong economic advantages, but many clients are reluctant to implicitly trust a third-party cloud provider. To address these security concerns, data may be transmitted and stored in encrypted form. Major challenges exist concerning the aspects of the generation, distribution, and usage of encryption keys in cloud systems,...

The authors propose several methods to speed up the facility location, and the single link and the complete link clustering algorithms. The local search algorithm for the facility location is accelerated by introducing several space partitioning methods and a parallelisation on the CPU of a standard desktop computer. The influence...

In this paper, the authors investigate on-demand data services for high-speed trains via a cellular/infostation integrated network. Service requests and acknowledgements are sent through the cellular network to a content server, while data delivery is achieved via trackside infostations. The optimal resource allocation problem is formulated by taking account of...

With the growing demand of Internet services, network operators have put significant efforts to improve network error resilience and efficiency. Since there exist different wired/wireless technologies for Internet access such as Digital Subscriber Line (DSL), Ethernet, and worldwide interoperability for microwave access (WiMax), a mobile host can use multiple access...

Financial and environmental considerations have motivated a trend in wireless communication network design and operation to minimize the amount of energy consumption. Such a trend is referred to as green radio communications. In this paper, network cooperation is investigated as a means of energy saving. Networks with overlapped coverage can...

In wireless sensor networks, adversaries can make use of traffic information to locate the monitored objects, e.g., to hunt endangered animals or kill soldiers. In this paper, the authors first define a hotspot phenomenon that causes an obvious inconsistency in the network traffic pattern due to a large volume of...

This paper introduces a novel multi-copy routing protocol, called Self Adaptive Utility-based Routing Protocol (SAURP), for Delay Tolerant Networks (DTNs) that are possibly composed of a vast number of devices in miniature such as smart phones of heterogeneous capacities in terms of energy resources and buffer spaces. SAURP is characterized...

Monitoring trail (m-trail) has been proposed as an effective approach for link failure localization in all-optical WDM (Wavelength Division Multiplexing) mesh networks. Previous studies in failure localization rely on alarm dissemination via control plane signaling such that the network controller can collect the flooded alarms to form an alarm code...

To prevent configuration errors, highly configurable software often allows defining constraints over the available options. As these constraints can be complex, fixing a configuration that violates one or more constraints can be challenging. Although several fix-generation approaches exist, their applicability is limited because they typically generate only one fix, failing...

The paper presents a novel algebraic framework for specification and design of model synchronization tools. The basic premise is that synchronization procedures, and hence algebraic operations modeling them, are diagrammatic: they take a configuration (diagram) of models and mappings as their input and produce a diagram as the output. Many...

The increase in scale and complexity of large compute clusters motivates a need for representative workload bench-marks to evaluate the performance impact of system changes, so as to assist in designing better scheduling algorithms and in carrying out management activities. To achieve this goal, it is necessary to construct workload...

State consistency in safety-critical distributed systems is mandatory for synchronizing distributed decisions as found in dynamic Time Division Multiple Access (TDMA) schedules in the presence of faults. A TDMA schedule that supports networked systems making decisions at run time is sensitive to transient faults, because stations can make incorrect local...

For Peer-To-Peer (P2P) networks continually to flourish, QoS provision is critical. However, the P2P networks are notoriously dynamic and heterogeneous. As a result, QoS provision in P2P networks is a challenging task with nodes of the varying and intermittent throughput. This raises a fundamental problem: is stable and delicate QoS...

In Cognitive Radio (CR) networks, users are allowed to dynamically access the temporally unused channels to recycle the spectrum for better throughput. However, the dynamic channel availability also results in the highly variable and intermittent download to the users, which directly threats the on-top applications, especially for real-time service such...

The newly emerged vehicular ad hoc network adopts the contention based IEEE 802.11 DCF as its MAC. While it has been extensively studied in the stationary indoor environment (e.g., WLAN), the performance of DCF in the highly mobile vehicular environment is still unclear. On addressing this issue, the authors propose...

High throughput and lifetime are both crucial design objectives for a number of multi-hop wireless network applications. As these two objectives are often in conflict with each other, it naturally becomes important to identify the tradeoffs between them. Several works in the literature have focused on improving one or the...

The authors present a number of significant engineering insights on what makes a good configuration for medium-to large-size WMNs when the objective function is to maximize the minimum throughput among all flows. For this, they first develop efficient and exact computational tools using column generation with greedy pricing that allow...

This paper investigates cross-layer design in multi-hop wireless networks with random access. Due to the complexity of the problem, the authors study cross-layer design with a simple slotted ALOHA Medium Access Control (MAC) protocol without considering any network dynamics. Firstly, they study the optimal joint configuration of routing and MAC...

Cloud computing promises on-demand provisioning of resource to applications and services. To deal with dynamically fluctuating resource demands, market-driven resource allocation has been proposed and recently implemented by commercial cloud providers like Amazon EC2. In this environment, cloud resources are offered in distinct types of Virtual Machines (VMs) and the...

With the increasing popularity of cloud computing, Hadoop has become a widely used open source cloud computing framework for large scale data processing. However, few efforts have been made to demonstrate the applicability of Hadoop to various real-world application scenarios in fields other than server side computations such as web...

With limited coverage of wireless networks and frequent roaming of mobile users, providing a seamless communication service poses a technical challenge. In the authors' previous research, they presented a supernode system architecture that employs the Delay-Tolerant Network (DTN) concept to provide seamless communications for roaming users over interconnected heterogeneous wireless...

In this paper, the authors consider a wireless communication network for both local nodes residing in densely populated hotspots and nomadic nodes roaming in a large area. Wireless Local Area Networks (WLANs) are deployed in the hotspots, while a Delay/disruption Tolerant Network (DTN) provides services to nomadic nodes in the...

Smart Grid (SG) communication has recently received significant attentions to facilitate intelligent and distributed electric power transmission systems. However, communication trust and security issues still present practical concerns to the deployment of SG. In this paper, to cope with these challenging concerns, the authors propose light-weight message authentication scheme features...

With the increasing need for networked applications and distributed resource sharing, there is a strong incentive for an open large-scale service infrastructure operating over multi-domain and multi-technology networks. Service discovery, as an essential support function of such an infrastructure, is a crucial current research challenge. Although a few survey papers...

The increase in scale and complexity of large compute clusters motivates a need for representative workload bench-marks to evaluate the performance impact of system changes, so as to assist in designing better scheduling algorithms and in carrying out management activities. To achieve this goal, it is necessary to construct workload...

Financial and environmental considerations have motivated a trend in wireless communication network design and operation to minimize the amount of energy consumption. Such a trend is referred to as green radio communications. In this paper, network cooperation is investigated as a means of energy saving. Networks with overlapped coverage can...

Embedding of Virtual Network (VN) requests on top of a shared physical network poses an intriguing combination of theoretical and practical challenges. Two major problems with the state-of-the-art VN embedding algorithms are their indifference to the underlying substrate topology and their lack of re-optimization mechanisms for already embedded VN requests....

State consistency in safety-critical distributed systems is mandatory for synchronizing distributed decisions as found in dynamic Time Division Multiple Access (TDMA) schedules in the presence of faults. A TDMA schedule that supports networked systems making decisions at run time is sensitive to transient faults, because stations can make incorrect local...

Although Compressed Sensing (CS) has been envisioned as a useful technique to improve the performance of Wireless Sensor Networks (WSNs), it is still not very clear how exactly it will be applied and how big the improvements will be. In this paper, the authors propose two different ways (plain-CS and...

The authors focus on efficient algorithms for resource allocation problems in large wireless networks. They first investigate the link scheduling problem and identify the properties that make it possible to compute solutions efficiently. They, then show that the node on-off scheduling problem shares these features and is amenable to the...

Paging for multicore processors extends the classical paging problem to a setting in which several processes simultaneously share the cache. Recently, Hassidim studied cache eviction policies for multicores under the traditional competitive analysis metric, showing that LRU is not competitive against an offline policy that has the power of arbitrarily...

Interference is an unavoidable property of the wireless communication medium and, in sensor networks, such interference is exacerbated due to the energy-starved nature of the network devices themselves. In the presence of antagonistic interference, reliable communication in sensor networks becomes an extremely challenging problem that, in recent years, has attracted...

The problem of Internet intrusions has become a world-wide security concern. To protect computer users from malicious attacks, Intrusion Detection Systems (IDSs) are designed to monitor network traffic and computer activities in order to alert users about suspicious intrusions. Collaboration among IDSs allows users to benefit from the collective knowledge...

Keyword search is one of the most effective paradigms for information discovery. One of the key advantages of keyword search querying is its simplicity. There is an increasing need for allowing ordinary users to issue keyword queries without any knowledge of the database schema. The retrieval unit of keyword search...

Pointing at displays from a distance is becoming a common scenario for controlling computers and entertainment systems. Several devices use direct-pointing methods, where the user points a hand-held device at targets on a screen, but these often suffer from accuracy problems. Many techniques have been explored for improving mouse-based pointing,...

To fully benefit from the all IP convergence, it should be possible for a user not only to access services ubiquitously and at any time, but also to automatically and seamlessly transfer ongoing communication between different devices. This paper investigates the problem space of supporting Session Mobility (SM) with IMS...

Presentational XML documents, such as XHTML or Presentation MathML, use XML tags mainly for formatting purposes, while descriptive XML applications, such as a well-structured movie database, use tags to structure data items in a semantically meaningful way. There is little semantic connection between tags in a presentational XML document and...

Cichon, Golebiewski and Kutylowski proposed a technique for "Key redistribution" in sensor networks. The idea is that long-term keys held by the sensor nodes are used to encrypt temporal keys that a base station then broadcasts to the network. The temporal keys are used as session keys by the nodes...

The wireless medium must be effectively shared in an ad hoc network. The multihop nature of the network demands it, with packets often requiring several transmissions in order to reach their destination. This paper describes a mechanism for improving the IEEE 802.11 MAC specifically for ad hoc networks. The Forward...

In this paper, the authors present a trust-based framework for message propagation and evaluation in vehicular ad-hoc networks where peers share information regarding road condition or safety and others provide opinions about whether the information can be trusted. More specifically, their trust-based message propagation model collects and propagates peers' opinions...

Cyber intrusion is becoming an increasingly global and urgent problem. Intrusion Detection Systems (IDSs) are deployed to identify intrusions and mitigate their damage. A stand alone IDS does not have complete information or knowledge to detect intrusions. A Collaborative Intrusion Detection Network (CIDN) consists in a set of cooperating IDSs...

Intrusion Detection Systems (IDSs) are designed to monitor network traffic and computer activities in order to alert users about suspicious intrusions. Collaboration among IDSs allows users to benefit from the collective knowledge and information from their collaborators and achieve more accurate intrusion detection. However, most existing collaborative intrusion detection networks...

An effective Collaborative Intrusion Detection Network (CIDN) allows distributed Intrusion Detection Systems (IDSes) to collaborate and share their knowledge and opinions about intrusions, to enhance the overall accuracy of intrusion assessment as well as the ability of detecting new classes of intrusions. Towards this goal, the authors propose a distributed...

Cooperation between Intrusion Detection Systems (IDSs) allows collective information and experience from a network of IDSs to be shared to improve the accuracy of detection. A critical component of a collaborative network is the mechanism of feedback aggregation in which each IDS makes an overall security evaluation based on peers...

In the standard definition of a commitment scheme, the sender commits to a message and immediately sends the commitment to the recipient interested in it. However, the sender may not always know at the time of commitment who will become interested in verifying it. Further, when the interested party does...

The authors consider User-Private Information Retrieval (UPIR), an interesting alternative to Private Information Retrieval (PIR) introduced by Domingo-Ferrer et al.. In UPIR, the database knows which records have been retrieved, but does not know the identity of the person making the query. The goal of UPIR, then, is to disguise...

Cloud computing confers strong economic advantages, but many clients are reluctant to implicitly trust a third-party cloud provider. To address these security concerns, data may be transmitted and stored in encrypted form. Major challenges exist concerning the aspects of the generation, distribution, and usage of encryption keys in cloud systems,...

This paper investigates a new approach to analyze symmetric ciphers by dividing the algorithms to consecutive sub-ciphers and then evaluating them separately. This attack is suitable for ciphers with simple key schedules and having block sizes smaller than key lengths. The authors have successfully applied this multidimensional approach to the...

The authors give a protocol for multi-server information-theoretic private information retrieval which achieves the theoretical limit for Byzantine robustness. That is, the protocol can allow a client to successfully complete queries and identify server misbehavior in the presence of the maximum possible number of malicious servers. They have implemented their...

Without direct path, information delivery in sparse Delay Tolerant Networks (DTNs) typically relies on intermittent relays, making the transmission not only unreliable but also time consuming. To make the matter even worse, the source nodes may transmit some encrypted "Junk" information, similar as the spam emails in current mail systems,...

Smart community is an emerging Internet of Things application. It supports a variety of high-value automated services such as pervasive healthcare through a multi-hop community network of smart homes in a local residential region. In this paper, the authors study privacy preserving data communication between patients and an online healthcare...

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